Slice your steak very thin against the grain and place into a large bowl. Mix the marinade ingredients and pour over the sliced steak. Let is sit (covered in the fridge) for 15 mins or so.
Meanwhile, whisk the sauce ingredients and set aside. Heat the 1 tbsp of sesame (or olive) oil in a large non-stick saute pan (or wok if you have one!) over medium high heat. It's important to get your pan HOT. Once heated, add in the sirloin along with any marinade.
Cook 2-3 mins each side until browned and crispy. You may need to do this in batches depending on how big your pan is. You don't want to overcrowd the meat. Once cooked through, remove from pan.
Add the additional tbsp of oil to the hot pan and add in your broccoli and cashews, scraping up any brown bits in the pan. Saute with a pinch of salt for 3-4 mins until the broccoli begins to turn bright green. Add the beef back to the pan along with the sauce, and stir for 1-2 mins until it thickens a bit and broccoli is cooked to your desired doneness. Serve over caulirice or carrot noodles. Enjoy!